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HAWAII  AGRICULTURAL  EXPERIMENT  STATION 

HONOLULU,  HAWAII 

BULLETIN  No.  49 


Under  the  supervision  of  the 
UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 


THE  ACID  LIME  FRUIT  IN  HAWAII 


BY 


W.  T.  POPE,  Horticulturist 


Issued  July  9,  1923 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 

192S 


HAWAII  AGRICULTURAL  EXPERIMENT  STATION 

HONOLULU,  HAWAII 

BULLETIN  No.  49 


Under  the  supervision  of  the 
UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 


THE  ACID  LIME  FRUIT  IN  HAWAII 


BY 


W.  T.  POPE,  Horticulturist 


Issued  July  9,  1923 


J* 


WASHINGTON 
GOVERNMENT  PRINTING   OFFICE 

1923 


HAWAII  AGRICULTURAL  EXPERIMENT  STATION,  HONOLULU. 

[Under   the  supervision  of   the   States   Relations   Service,   United   States   Department   of 

Agriculture.] 

A.  C.  Tbue,  Director. 

E.  W.  Allen,  Chief,  Office  of  Experiment  Stations. 

Walter  H.  Evans,  Chief,  Division  of  Insular  Stations,  Office  of  Experiment 
Stations. 

STATION  STAFF. 

J.  M.  Westgate,  Agronomist  in  Charge. 
W.  T.  Pope,  Horticulturist. 
H.  L.  Chung,  Specialist  in  Tropical  Agronomy. 
J.  C.  Rippebton,  Chemist. 

R.  A.   Goff,  In  Charge  of  Olenwood  Substation  and  Extension  Agent  for 
Island  of  Hawaii. 

Nellie  A.  Russell,  Collaborator  in  Home  Economics. 


THE  ACID  LIME  FRUIT  IN  HAWAII. 


CONTENTS. 


Page. 

Introduction 1 

Varieties 1 

Culture 4 

Insect  pests 10 

Fungus  diseases 12 


Paga 

Spraying    appliances 13 

Composition    of   the   lime 14 

Commercial    products 15 

Recipes 16 

Summary 19 


INTRODUCTION. 

The  acid  lime  {Citrus  aurantifolia)  is  commonly  found  growing 
in  both  the  semiwild  and  the  cultivated  state  in  most  tropical  and 
subtropical  countries.  Some  authorities  are  of  the  opinion  that  it  is 
indigenous  to  India  because  of  its  presence  in  the  native  vegetation. 
In  the  Malay  Archipelago,  or  Malaysia,  and  other  islands  of  the 
Pacific  Ocean  it  is  grown  for  home  consumption,  and  in  the  West- 
Indies,  tropical  Mexico,  and  to  a  lesser  extent  in  southern  Florida,  it 
is  cultivated  for  commercial  use.  The  lime  was  introduced  into 
Hawaii  early  in  the  nineteenth  century  and  seems  to  be  the  most 
readily  adapted  of  any  of  the  citrus  fruits  to  island  conditions. 

The  tree  has  many  points  in  its  favor  for  profitable  culture  in 
Hawaii.  It  can  be  propagated  in  several  ways,  will  thrive  in  a  great 
variety  of  soils,  and  produce  large  crops  of  fruit  during  the  greater 
part  of  the  year.  Moreover,  it  withstands  drought  remarkably  well 
and  is  not  as  susceptible  to  insect  attack  and  disease  as  are  most  of 
the  other  citrus  fruits  on  the  island.  The  fruit  is  not  imported  1 
into  Hawaii,  and  therefore  meets  with  less  local  competition  than 
do  the  orange,  lemon,  and  grapefruit. 

The  fruit  has  many  uses  which  the  orange  and  lemon  can  not  well 
serve.  The  demand  for  lime  juice  to  improve  the  palatability  of 
many  kinds  of  tropical  fruits  as  well  as  for  seasoning  fish  and  meat 
is  naturally  larger  in  Hawaii  than  it  is  in  countries  where  there  is 
greater  variation  in  temperature.  The  rapidly  increasing  popula- 
tion and  the  widespread  demand  for  the  fruit  seem  to  assure  local 
development  of  the  lime-fruit  industry  and  to  call  for  the  selection 
of  varieties  of  high  quality  for  home  consumption  as  well  as  for  the 
market.  At  least  one*  lime  tree  should  be  grown  in  every  home  gar- 
den in  the  Territory. 

VARIETIES. 

The  lime  is  closely  related  to  the  lemon,  orange,  mandarin,  pomelo, 
and  shaddock.  Botanically,  it  belongs  to  the  genus  Citrus.  It  is 
known  by  several  specific  names,  being  described  by  various  writers 


i  The  lime  is  too   tender  to  be   grown   commercially   in   California   for   exportation   to 
Hawaii. 


2  BULLETIN  49,   HAWAII   AGRICULTURAL  EXPERIMENT  STATION. 

as  Citrus  Umetta,  C.  medica  acida,  and  C.  aurantifolia,  the  last  of 
which,  given  by  W.  T.  Swingle,2  is  the  one  most  generally  accepted. 
Christman  calls  it  Limonia  auranti folia,  a  technical  name  which 
includes  both  the  sweet  and  the  sour,  or  acid,  varieties  of  lime. 

Varietal  names  of  limes  are  really  group  names  in  many  instances, 
for  they  are  based  on  group  characters  rather  than  on  varietal  char- 
acters. Many  so-called  varieties  have  been  described  by  horticul- 
tural writers,  but  only  four,  namely,  Kusaie,  West  Indian,  Eangpur, 
and  Tahiti,  with  possibly  their  closely  related  species,  were  experi- 
mented with  by  the  experiment  station  (PI.  I). 

KUSAIE. 

The  Kusaie  lime  (PI.  I)  is  said  to  have  been  developed  on  the 
island  of  Kusaie,  or  Strongs  Island,  Micronesia,  by  early  Spanish 
settlers.  In  1885  it  was  introduced  into  Hawaii,  where  it  has  stead- 
ily gained  in  favor  and  is  considered  the  finest  of  the  four  varieties 
of  limes  tested  by  the  experiment  station.  The  variety  reproduces 
from  seed  with  characters  that  are  superior  to  those  of  the  parent, 
is  not  as  thorny  as  the  latter,  and  does  not  produce  so  many  seeds. 

The  Kusaie  lime  tree  varies  in  size  from  a  mere  shrubby  bush  to 
a  well-formed  tree  attaining  a  height  of  10  feet  (PI.  Ill,  Fig.  1). 
When  allowed  to  grow  naturally  the  tree  develops  a  spreading, 
bushy  tendency  at  the  top,  with  lower  branches  touching  the  ground ; 
and  when  reproduced  from  seed  it  usually  sends  up  root  sprouts 
which  eventually  develop  into  thickets.  This  latter  tendency,  how- 
ever, can  be  overcome  by  budding  the  tree  upon  some  other  citrus 
species  which  does  not  send  up  root  sprouts.  The  Kusaie  is  ever- 
green and  bears  leaves  that  are  rather  small  in  size  and  somewhat 
rounded  at  the  apex.  It  is  generally  prolific  and  begins  to  bear 
during  the  second  or  third  year,  continuing  to  produce  almost 
throughout  the  year. 

Fruit:  Form,  oval,  spherical,  or  oblate;  apex  flattened  or  de- 
pressed, with  a  small  sharp-pointed  nipple;  size,  medium  to  large, 
the  diameter  ranging  from  2  to  2£  inches;  rind  medium  to  thin, 
light  lemon-yellow,  and  colors  irregularly;  oil  cells  numerous;  seg- 
ments vary  from  6  to  10 ;  dividing  tissues  thin ;  pulp  vesicles  spindle- 
shaped;  flesh  usually  of  a  clear  honey -yellow  color;  juice  abundant, 
colorless  or  transparent,  with  a  characteristic  flavor;  central  pith 
usually  open ;  seeds  plump  and  few  in  number. 

All  of  the  Kusaie  trees  at  the  experiment  station  are  vigorous 
and  prolific,  some  of  them  having  started  to  bear  at  18  months  of 
age.  In  their  fourth  year  these  trees  each  produced  about  400  fruits 
which  averaged  40  pounds  to  the  tree.  The  Qrop  of  1920,  11  years 
later,  amounted  to  2,000  fruits  per  tree,  or  on  the  average,  nearly 
200  pounds  per  tree.  The  trees  have  borne  almost  continuously  since 
coming  into  bearing.  On  May  16,  1922,  they  were  8  to  10  feet  high, 
heavily  laden  with  fruit,  and  had  spreading  tops. 

WEST  INDIAN. 

The  West  Indian  variety,  also  called  the  Mexican,  Samoan,  and 
Hawaiian  lime,  is  probably  the  most  extensively  used  lime  in  Amer- 

2  Standard  Cyclopedia  of  Hort,  v.  II,  p.  782. 


Bui.  49,    Hawaii   Agr.   Expt.   Station. 


Plate  I 


o  < 

..  Q 

<f)   z 
LU  — 

Ik 

o  •> 

hi  C 


Bui.  49,    Hawaii   Agr.    Expt.   Station. 


Plate   I 


KUSAIE    LIMES    GROWN    AT    THE    HAWAII    STATION. 


Bui.  49,    Hawaii   Agr.   Expt.   Station. 


Plate  III 


Fig.   I. — Kusa'E  lime  tree.     Experimental  orchard,  Hawaii  Station. 


Fig.  2. — Left,   shield-bud,   lime   on   sour   orange   stock.     Right,   bark- 
graft,    LIME   ON    SOUR    ORANGE    STOCK.       BOTH    74    DAYS   AFTER    GRAFTING. 


Bui.  49     Hawaii    Agr.    Expt.   Station. 


Plate  IV. 


The  West   Indian   lime  was  the  first  variety  to  reach   Hawai 
Imany  it  is  called  the  Hawaiian  lime. 


By 


Bui.  49,    Hawaii    Agr.    Expt.   Station. 


Plate  V. 


Rangpur  lime.     Grown  at  the  Hawaii  Station. 


Bui.  49,    Hawaii    Agr.    Expt.   Station. 


Plate  VI. 


Bearss,  a  seedless  lime,  an   improved  type  of  Tahitian. 


THE   ACID   LIME    FRUIT    IN    HAWAII.  6 

ica  (PI.  IV).  It  is  grown  mainly  in  the  "West  Indies,  Florida,  and 
Mexico.  This  variety  is  a  shrubby  bush  that  attains  a  height  of 
from  6  to  10  feet.  It' is  well  provided  with  small,  sharp  thorns,  and 
with  rather  small,  light-green  foliage. 

Fruit :  Ripens  practically  the  year  around.  Form,  oblong  to  oval: 
size  about  2  or  21  inches  long  (large  size  range  from  II  to  2  inches 
in  diameter)  ;  surface  light  lemon-yellow ;  apex  usually  smooth  with 
a  blunt  point  when  nippled:  base  usually  smooth  and  occasionally 
elongated  to  neck  form ;  rind  smooth  and  very  thin ;  oil  cells  numer- 
ous; segments  10  or  less  in  number  and  distinctly  marked;  divid- 
ing tissue  thin:  flesh  fine-grained  and  of  light  green  color:  pulp 
vesicles  small  and  spindle-shaped:  juice  plentiful  and  of  translucent 
color:  pulp  soft  to  melting;  acid  very  strong,  the  flavor  being  dis- 
tinctly of  the  lime:  central  pith  open  and  small:  seeds  few  to  many, 
and  in  shape  flat,  like  a  wedge,  to  rather  pointed. 

Several  closely  related  forms  grow  in  Florida.3  Palmetto,  which 
is  the  result  of  a  cross  between  West  Indian  and  the  common  lemon, 
and  Everglade,  the  progeny  of  \Vest  Indian  with  pollen  of  the 
pomelo,  are  said  to  be  excellent  fruits.  Thornless,  another  lime  of 
the  Mexican  type  from  British  Dominica,  developed  as  a  sport  about 
1891.     Absence  of  thorns  is  a  desirable  feature  in  lime  culture. 

RANGPUR. 

The  Rangpur,  also  known  as  Rungpur  or  Rungpor,4  originated  in 
India  (PL  V).  Although  an  acid  fruit  it  is  not  considered  a  true 
lime.  It  is  hardier  than  the  true  lime  and  is  said  to  belong  to  the 
Suntara  orange  group  of  India.  The  color  of  the  fruit,  the  ease 
with  which  the  peel  separates  from  the  pulp  and  the  segments  from 
each  other,  as  well  as  its  peculiar  flavor,  are  characters  indicating 
relationship  to  the  well-known  mandarin  group  of  citrus  fruits. 
Owing  to  the  character  of  the  fruit  and  certain  habits  of  the  tree, 
the  Rangpur  is  grouped  with  the  lime  only  provisionally.  Its 
introduction  into  Florida  by  means  of  seeds  has  doubtless  been 
the  means  of  its  reaching  Hawaii.  Several  trees  of  this  variety, 
introduced  into  Hawaii  from  Australia  by  Judge  S.  B.  Dole,  have 
made  good  growth  and  are  prolific. 

The  Rangpur  lime  tree  is  small  and  of  spreading  habit.  Its 
branches  are  thorny,  the  foliage  is  rather  sparse,  and  the  small, 
light-green  leaves  have  rounded  apexes  but  no  stipules. 

Fruit :  In  season  in  fall  and  winter.  Form,  round,  oblate,  tending 
toward  obovate,  occasionally  necked:  apical  nipple  sharp-pointed: 
apex  usually  flat:  base  depressed  at  stem,  or  ridged  when  necked: 
size  medium  with  diameter  of  2  or  2-|  inches;  rind  inclined  to  be 
rough,  medium  in  thickness,  easily  separated  from  the  pulp,  and 
of  irregular  color  that  becomes  orange  red  on  ripening:  segments 
regular,  7  or  8  in  number,  and  easy  to  separate ;  pulp  vesicles  large, 
plump,  and  pointed;  flesh  orange-colored;  juice  plentiful  and  of  an 
agreeable  flavor  that  is  peculiar  to  the  variety:  central  pith  small 
and  open;  seeds  plump,  7  to  18  in  number,  with  little  or  no  point, 
and  of  a  greenish  hue  on  the  inside. 

«U.  S.  Dept.  Agr.  Yearbook,  190-3,  pp.  279-281. 

4  Hume,  H.  H.     Citrus  fruits  and  their  culture.     1915,  p.  142. 


4  BULLETIN  49,   HAWAII   AGRICULTURAL  EXPERIMENT   STATION. 

In  1917  the  experiment  station  received  several  specimens  of 
Rangpur  buds  which  were  grafted  upon  sour-orange  stock.  These 
trees  are  making  such  thrifty  growth  that  it  is  deemed  worth  while 
propagating  considerable  new  stock  from  them  for  further  ex- 
periment. 

TAHITI. 

The  Tahiti  (PL  VI)  is  supposed  to  be  a  sport  of  the  Persian 
variety  of  lime.  The  tree  attains  a  height  of  15  feet  and  forms  at  the 
top  a  dense  mass  of  foliage  which  presents  a  rounded  appearance. 
The  branches  are  set  with  small  spines  and  are  inclined  to  droop, 
and  the  dark-green  leaves  are  large  and  have  a  tendency  to  curl. 
The  fruiting  season  of  the  Tahiti  lime  is  during  the  fall  and  winter. 

Fruit:  Produced  in  abundance  and  is  borne  either  singly  or  in 
clusters;  frequently  well  hidden  by  the  foliage;  seedless;  size  me- 
dium to  large,  3  by  2^  inches;  apex  often  nippled  with  pistil  style, 
or  with  both  stigma  and  pistil  adhering ;  rind  green  to  lemon-yellow 
in  color,  smooth,  thin,  and  scattered  with  pit  depressions;  base 
necked  to  rounded;  calyx  adheres  firmly  to  fruit;  flesh  fine-grained 
and  of  greenish  color;  segments  irregular  in  number  but  usually 
average  10;  pulp  vesicles  cylindrical,  narrow,  and  somewhat  pointed; 
juice  plentiful,  almost  colorless,  and  of  agreeable  flavor;  acid 
strong;  central  pith  open  and  small. 

Two  improved  types  of  the  Tahiti  are  the  Bearss  and  the  Im- 
proved. Bearss  is  under  cultivation  in  Hawaii  and  is  highly  es- 
teemed on  account  of  the  prolificacy  of  the  tree  and  the  large,  seed- 
less fruit. 

CALAMONDIN. 

The  calamondin  {Citrus  mitis),5  erroneously  called  the  Chinese 
orange,  is  frequently  associated  with  the  lime,  for  which  it  is  some 
times  used  as  a  substitute. 

CULTURE. 

CLIMATE. 

Lime  trees  thrive  in  a  warm,  moist  climate  where  the  rainfall  is 
evenly  distributed  in  frequent  showers  and  varies  from  80  to  150 
inches  annually.  In  localities  where  moisture  is  lacking,  irrigation 
should  be  practiced  to  enable  the  trees  to  make  thrifty  growth.  It 
is  important  that  the  orchard  be  relatively  free  from  exposure  to  the 
force  of  high  wind,  otherwise  growth  will  be  retarded,  the  foliage 
and  flowers  seriousty  injured,  and  the  fruit  bruised  and  scarred.  In 
some  places  windbreaks  are  provided  to  protect  a  grove  that  is  not 
well  "located. 

SOIL. 

The  lime  grows  best  in  rich  sandy  or  gravelly  soil  which  is  well 
drained.  Porous  lava  soils  of  recent  formation,  geologically,  give 
excellent  results  when  they  occur  in  locations  of  abundant  rainfall. 
Stiff  clay  soils  are  not  suitable  because  they  give  rise  to  root  troubles. 
Impervious  substrata  can  be  shattered  by  the  use  of  dynamite. 

B  Bailey,  L.  H.     Standard  Cyclopedia  of  Hort.,  v.  II,  p.  784. 


THE    ACID   LIME    FRUIT    IX    HAWAII.  0 

TILLAGE. 

The  lime  tree  makes  the  same  demand  upon  the  soil  as  do  other 
trees  of  similar  size  and  the  fertility  of  the  soil  should  therefore  be 
maintained.  The  soil  should  be  thoroughly  tilled  to  keep  it  in  a 
suitable  condition  of  aeration  and  free  from  weed  growth.  Such 
tillage  will  result  in  conservation  of  soil  moisture,  improvement  in 
texture,  and  an  increase  in  the  productivity  of  the  soil. 

FERTILIZING. 

To  produce  the  most  profitable  crop  lime  trees  must  be  properly 
nourished.  In  Hawaii  many  lime  trees  do  fairly  well  without  till- 
age, irrigation,  or  fertilizers  of  any  kind;  nevertheless,  the  fruiting 
capacity  of  trees  reaching  a  high  degree  of  productivity  becomes  ab- 
normal through  intensive  cultivation,  and  heavy  bearing  can  be 
maintained  only  by  furnishing  the  trees  with  an  abundance  of  plant 
food.  This  may  be  given  in  the  form  of  a  fertilizing  material,  either 
as  farm  manure  or  commercial  fertilizer,  or  better  still,  the  two  may 
be  used  in  combination. 

Locations  naturally  differ  in  soil  and  climatic  conditions  and  each 
should  be  studied  separately  so  that  its  needs  may  be  determined.  As 
a  rule  the  soil  is  deficient  in  humus  wherever  citrus  fruits  are  grown 
commercially.  Farm  manure  should  be  applied  to  such  land  or  a 
leguminous  cover  crop  should  be  grown  to  furnish  green  manure. 
Many  growers  utilize  both. 

Farm  manure  is  one  of  the  best  general  fertilizers.  It  supplies  the 
soil  with  a  large  quantity  of  organic  matter,  which,  upon  decaying, 
improves  the  texture  of  the  soil  and  makes  readily  available  for  crop 
use  the  mineral  fertilizer  constituents  in  the  soil.  Farm  manure 
should  be  well  distributed  over  the  soil  and  then  immediately  turned 
under. 

Green  manure  is  furnished  by  growing  and  plowing  under  some 
leguminous  crop,  such  as  velvet  beans,  cowpeas,  pigeon  peas,  mungo 
beans,  and  the  like,  which  enrich  the  soil  in  nitrogenous  matter. 

Excess  of  nitrogen  in  the  soil  is  indicated  by  vigorous  growth  of 
the  trees,  dark-green  foliage,  and  a  small  amount  of  fruit  having 
a  thick  rind  and  very  fibrous  pulp.  Liberal  applications  of  potash 
with  the  nitrogen  tend  to  produce  greater  fruitfulness,  thinness  of 
rind,  and  less  fiber. 

Trees  which  it  is  desired  to  have  grow  rapidly  but  which  have 
not  attained  bearing  age  require  relatively  large  amounts  of  nitrogen 
and  much  less  potash  than  do  those  producing  heavy  crops.  Trees 
bearing  heavy  crops  require  a  fertilizer  having  high  percentages  of 
both  potash  and  phosphoric  acid. 

In  general  fruit  culture  young  trees  are  thought  to  require  phos- 
phoric acid,  potash,  and  nitrogen  in  the  proportions  of  6,  8,  and  -i 
per  cent,  respectively,  and  fruiting  trees  in  the  proportions  of  8.  12. 
and  *H  per  cent,  respectively. 

Table  1  -hows  the  kinds  and  amounts  of  constituents  that  might  be 
used  to  make  a  ton  of  fertilizer. 


BULLETIN  49,   HAWAII   AGRICULTURAL  EXPERIMENT   STATION. 
Table  1. — Fertilizer  mixture  for  lime  trees.1 


Constituent. 

For 
young 
trees. 

For 

bearing 

trees. 

Acid  phosphate 

Pounds. 
800 
314 
250 
190 
446 

Pound*. 
1  066 

High-grade  sulphate  of  potash 

470 

Nitrate  of  soda 

Sulphate  of  ammonia 

333 

Makeweight  (filler) 

131 

Total 

2,000 

2  000 

i  Hawaii  Sta.  Bui.  9,  p.  16. 

During  1913-1917  the  Department  of  Agriculture  of  the  island 
of  Dominica,  West  Indies,  conducted  fertilizer  experiments  on  lime 
trees  in  an  orchard  that  had  been  abandoned,  so  far  as  fertilizers 
were  concerned,  for  18  years  previous  to  1913.  The  effect  of  the 
fertilizers,  including  cultivation,  pruning,  and  the  like,  on  yield  of 
fruit,  is  shown  in  Table  2. 

Table  2.— Effects  of  different  fertilizers  on  yield  of  lime  trees  in  Dominica. 


Plat 
No. 


Treatment . 


Yields  per  acre  in  barrels  of  1& 
cubic  feet.1 


1915 

1916 

53 

62 

40 

% 

71 

98 

28 

40 

65 

99 

37 

76 

89 

126 

94 

172 

1917 


No  fertilizer 

5  tons  of  grass  mulch 

Dried  blood,  400  pounds 

Sulphate  of  potash,  150  pounds 

Sulphate  of  ammonia,  250  pounds 

Basic  slag,  400  pounds 

Dried  blood,  400  pounds,  with  basic  slag,  400  pounds 

Dried  blood,  400  pounds;  sulphate  of  potash,  150  pounds:  basic 
slag,  400  pounds 


23 
14  I 

17  i 

6  ! 
32 
16  ' 
28  ! 

24  I 


88 

m 

141 

70 
156 
127 
167 


1 A  barrel  of  4.^  cubic  feet  holds  about  1,500  limes,  which  weigh  about  150  pounds. 

The  soils  of  Hawaii  are  not  necessarily  of  the  same  type  as  those 
of  Dominica,  but  the  results  obtained  from  the  above-mentioned 
experiment  show  that  it  is  possible  to  increase  the  yield  of  lime  trees, 
although  unfertilized  for  some  time,  by  the  application  of  fertilizers, 
and  that  certain  fertilizers  are  more  effective  than  others  in  bringing 
about  greater  yields. 

PROPAGATION. 

L:me  trees  may  be  propagated  by  seeds,  root  sprouts,  cuttings, 
layerings,  and  by  grafting  and  budding.  The  most  general  method 
of  propagation  is  by  seed,  but  results  obtained  from  experiments 
show  that  the  most  practical  method  for  good  production  is  that  of 
grafting  and  budding. 

Seed. — The  seed  should  be  well  matured,  fresh,  and  well  filled.  It 
should  be  selected  from  the  most  vigorous  trees  and  be  thoroughly 
cleaned  to  reduce  the  possibility  of  its  being  destroyed  by  insects 
or  by  fermentation.  After  the  juice  and  pulp  have  been  washed 
from  it  and  superfluous  moisture  has  been  removed  from  the  outer 
coatings,  the  seed  should  be  planted  in  shallow  seed-sprouting  boxes 


THE   ACID   LIME   FRUIT   IN    HAWAII.  7 

of  sterilized  soil  and  covered  to  a  depth  of  about  one-half  inch,  or 
dropped  about  2  inches  apart  in  shallow  drills  laid  off  6  inches  apart. 
The  sand  should  then  be  well  packed  down.  Rich  soil  should  not  be 
used  because  it  is  likely  to  harbor  fungus  spores,  which  may  attack 
the  seedlings  and  cause  them  to  die. 

Propagating  boxes  should  be  kept  in  a  somewhat  sheltered  place 
where  there  is  good  light  and  a  reasonable  amount  of  moisture.  The 
seed  germinates  in  a  few  weeks  when  it  is  kept  at  the  right  tempera- 
ture and  sufficiently  moist. 

As  boon  as  they  are  about  2  inches  high  the  seedlings  should  be 
separated  and  transplanted,  each  to  a  3-inch  pot  of  rich  sandy  loam. 
An  inexpensive  pot  can  be  made  from  quart  cans  having  holes  perfo- 
rated in  the  bottom  to  allow  for  drainage.  The  holes  should  be 
covered  on  the  inside  with  pieces  of  pottery  or  tile  to  prevent  the 
soil  from  washing  out.  As  soon  as  the  roots  fill  the  soil  the  plantlets 
should  be  transferred  to  larger  containers.  Pot-bound  plants  are 
likely  to  make  stunted  growth.  When  they  are  10  or  15  inches  high, 
which  is  usually  10  or  12  months  after  the  seed  is  planted,  the  plants 
should  be  set  in  their  permanent  place  in  the  ground.  From  30  to 
50  per  cent  more  seeds  than  are  needed  should  be  planted  to  make 
allowance  for  loss  or  for  weak  and  inferior  seedlings. 

Root  sprouts^- — In  many  countries,  particularly  where  the  West 
Indian  or  Mexican  lime  is  grown,  young  trees  are  obtained  by  plant- 
ing root  sprouts  that  are  taken  from  older  trees.  The  Kusaie  lime 
occasionally  produces  such  sprouts  in  Hawaii.  The  grower  may 
induce  lime  trees  to  send  up  root  sprouts  by  digging  out  the  surface 
roots,  severing  them  either  wholly  or  in  part  from  the  parent,  and 
planting  them  with  one  end  left  protruding  above  ground. 

Cuttings. — Cuttings  of  sound,  matured  wood  may  be  rooted  in 
regular  cutting  benches.  The  cuttings  should  be  6  or  8  inches  long, 
bear  several  matured  buds,  and  be  set  firmly  in  the  ground  with  about 
2  inches  of  the  upper  ends  protruding  above  ground.  Rooted  cut- 
tings usually  do  not  have  very  desirable  root  systems. 

Layering. — This  method  of  propagation  consists  in  removing  a 
ring  of  bark  from  a  branch  just  below  where  it  is  desired  to  have  the 
roots  start  and  covering  the  branch  with  soil  until  such  time  as  it 
has  developed  new  roots.  The  branch  is  then  removed  to  its  perma- 
nent location  and  established  as  a  new  tree. 

Grafting  and  budding. — Methods  of  grafting  and  budding  have 
given  great  satisfaction  at  the  experiment  station  for  rapidly  propa- 
gating good  standard  lime  trees.  (PL  III,  Fig.  2.)  Ten  and  twelve- 
month-old seedlings  attaining  a  height  of  3  to  4  feet  and  the  diameter 
of  a  small  pencil  were  used  as  rooted  stocks  for  grafting  purposes. 
They  were  repotted  several  times  in  the  course  of  a  year  to  promote 
a  steady,  vigorous  growth,  and  about  two  weeks  before  budding  time 
were  given  an  abundance  of  water  in  which  a  small  quantity  of 
nitrate  of  soda  had  been  placed  to  improve  grafting  conditions. 

The  rooted  stock  should  be  vigorous  and  resistant  to  adverse  condi- 
tions if  a  new-budded  tree  having  health,  vigor,  and  quality  is  to  be 
established.  The  varieties  of  citrus  that  have  given  great  satisfaction 
at  the  experiment  station  for  grafting  are  the  rough  lemon,  sour 
orange,  pomelo,  and  shaddock.  The  station  has  bearing  trees  of  these 
varieties  which  furnish  seeds  for  the  production  of  seedlings  for  ex- 
perimental purposes. 
45087—23 2 


8  BULLETIN   49,   HAWAII    AGRICULTURAL  EXPERIMENT   STATION. 

Rough  lemon  seedlings  have  been  employed  by  horticulturists  for 
some  years  to  meet  the  need  for  strong  rootstocks  for  grafting  pur- 
poses. The  main  development  of  this  variety  has  been  toward  the 
production  of  vigorous  and  resistant  rootstocks.  The  fruit  of  the 
rough  lemon  is  rated  of  poor  quality  on  account  of  its  coarse,  thick, 
rough  skin. 

The  sour-orange  stock  is  produced  from  seeds  of  the  wild  sour 
orange  which  now  grows  in  abundance  in  parts  of  Florida.  Its 
greatest  value  lies  in  its  resistant  rootstock.  Results  obtained  from 
experiments  indicate  that  it  has  about  the  same  value  as  the  rough 
lemon  for  propagating  purposes. 

Pomelo  seedlings,  or  what  are  commonly  known  as  grapefruit 
seedlings,  make  vigorous  stock  on  which  to  graft  the  lime. 

The  shaddock,  a  fruit  of  oriental  origin,  also  makes  a  strong  arid 
rapidly  growing  stock  for  citrus  in  Hawaii. 

Scions  should  be  selected  only  from  vigorous  and  prolific  trees  the 
fruit  of  which  is  known  to  have  a  combination  of  the  best  qualities 
that  can  be  found.  They  should  be  about  three-sixteenths  inch  in 
diameter  and  of  green  fruit- wood  possessing  healthy  buds,  which 
have  not  begun  to  swell  with  growth. 

Of  the  several  forms  of  union  such  as  shield-budding,  bark,  side, 
and  whip  grafting,  that  of  bark  grafting  is  best.  To  effect  this  union 
the  stock  should  be  cut  off  almost  at  right  angles  to  the  vertical  axis 
and  made  smooth.  A  downward  slit  should  be  made  14  inches  long, 
beginning  at  the  top  and  extending  through  the  bark,  to  permit  of  its 
spreading  when  the  scion  is  inserted.  As  soon  as  the  scion  is  cut  the 
lower  portion  should  be  beveled  for  1}  inches  and  the  flattened  end 
inserted  in  the  stock  between  the  bark  and  the  sapwood  so  that  the 
cambium  edges  will  be  in  proper  contact.  The  union  should  then 
be  firmly  bound  with  cotton  twine  or  moist  tying  raffia,  and  the  cut 
surface  sealed  with  grafting  wax  to  keep  out  insects,  shed  water,  and 
prevent  the  delicate  tissues  from  drying  out. 

When  shield-budding  is  practiced  the  shield  should  be  put  into  an 
inverted  T-shaped  incision  made  in  the  bark  of  the  stock  several 
inches  above  the  ground.  It  should  then  be  pushed  down  until  the 
cambiums  are  in  proper  contact,  firmly  tied  in  place,  and  wound  with 
waxed  tape  for  protection.  Care  should  be  exercised  to  raise  the  bark 
of  the  stock  without  injuring  the  cambium.  The  foliaged  top  of  the 
stock,  or  a  portion  of  it,  should  be  left  standing  until  the  bud  has 
made  a  growth  of  several  inches.  It  should  then  be  severed  from  the 
stock  close  to  the  bud  with  a  slanting  cut.  The  waxed  tape  should 
be  removed  about  six  days  after  the  operation  and  the  binding  string 
several  days  later. 

Experiments  which  were  made  with  bark  grafting  and  shield 
budding  at  the  experiment  station  showed  the  former  method  to  be 
the  better  of  the  two  in  giving  a  strong  union  and  an  early  upright 
growth. 

The  growth  of  grafted  trees  may  be  continued  in  gallon  containers. 
The  young  trees  should  be  exposed  to  full  sunlight  so  that  they  will 
become  hardy  preparatory  to  being  set  permanently  in  the  orchard 
or  home  yard.  At  the  end  of  10  or  12  months  they  should  be  12  or 
15  inches  high. 


THE    ACID   LIME    FRUIT   IN    HAWAII.  9 

PLANTING. 

The  lime  tree,  either  seedling  or  grafted  stock,  should  be  at  least 
a  year  old  before  it  is  transplanted  to  its.  permanent  location.  It 
should  be  carefully  removed  from  the  container  with  the  ball  of 
earth  adhering  to  the  roots  so  that  the  root  system  will  be  injured 
as  little  as  possible.  This  can  easily  be  done  by  inverting  the  pot 
and  tapping  it  gently  against  some  solid  bod}".  The  plant  can  easily 
be  slipped  from  the  container  if  the  soil  is  slightly  moistened  some 
hours  before  being  taken  to  the  field.  If  the  trees  are  grown  in  tin 
cans  tin-cutting  shears  may  be  used  to  open  one  side  of  the  container 
to  release  the  roots  without  injury. 

The  tree  should  have  an  open  area  of  at  least  8  feet  across  and  be 
away  from  large  trees  which  might  shade  it  and  from  such  vigorous 
plant  growth  as  would  contend  with  it  for  food.  It  should  be  set  in 
a  hole  dug  fully  2  feet  deep  with  a  diameter  of  2  feet,  be  sheltered 
from  strong  winds,  and  be  exposed  to  direct  sunlight.  Before  the 
tree  is  planted  the  hole  should  be  partly  filled  with  loose  surface 
soil  which  has  been  enriched  with  several  shovelfuls  of  well-rotted 
farm  manure.  Once  the  tree  is  in  place  the  mass  of  soil  adhering  to 
the  roots  should  be  loosened  a  trifle.  The  roots  that  have  started 
to  grow  in  a  circle  should  be  straightened  so  that  they  will  grow  in 
an  outward  direction.  Soil  should  then  be  filled  in  against  that 
surrounding  the  roots  and  pressed  down. 

The  soil  immediately  surrounding  the  tree  should  be  several  inches 
lower  than  the  natural  surface  to  form  a  slight  basin  which  will 
hold  water  until  the  tree  has  had  ample  time  to  settle.  After  being 
planted  the  tree  should  be  given  a  thorough  watering  to  induce 
capillary  action  of  the  moisture  in  the  soil.  It  should  then  be  left 
alone  for  several  days  and  after  that  watered  once  a  week  or  once  in 
every  two  weeks.    Daily  watering  is  detrimental  to  growth. 

When  it  is  properly  planted  the  tree  should  stand  straight  and 
firm  or,  if  it  is  exposed  to  the  wind,  it  should  lean  slightly  toward 
the  direction  whence  the  prevailing  wind  blows  so  that  it  will  be 
able  to  make  a  perfectly  erect  growth  when  influenced  by  the  wind. 
The  ground  immediately  surrounding  the  tree  should  be  kept  free 
from  grass,  weeds,  and  shrubbery  which  would  utilize  the  plant  food 
needed  by  the  lime  tree,  and  the  soil  should  occasionally  be  stirred 
to  facilitate  the  release  of  plant  food  and  keep  it  sweet. 

Seedling  trees  do  not  need  to  be  supported  with  a  stake  during 
the  first  year  or  two  as  do  other  kinds  of  trees.  Grafted  trees,  how- 
ever, should  be  supported  and  protected  with  a  stake.  The  only 
pruning  necessary  is  the  removal  of  dead  wood  and  stray  branches 
which  might  hinder  development. 

In  orchard  planting  small  lime  trees  should  be  set  in  rows  about 
15  feet  apart  each  way.  This  will  permit  of  the  growing  of  193 
trees  to  the  acre.  If  planted  so  that  the  trees  in  one  row*  come 
opposite  the  center  of  the  spaces  in  adjoining  rows  a  greater  number 
can  be  grown  in  a  given  space. 

Young  trees  may  be  set  in  hedge  formation  and  developed  into  a 
wide  fence.  Such  a  dense  row  will  be  invaluable  not  only  as  a  fence 
but  also  for  the  production  of  a  large  quantity  of  fruit  from  a  small 
area. 


10        BULLETIN   49,    HAWAII    AGRICULTURAL   EXPERIMENT    STATION. 

INSECT  PESTS  AND  REMEDIES  FOR  THEM. 

The  lime  tree  is  attacked  by  several  insect  pests  and  fungus  dis- 
eases. In  Hawaii  it  is.  however,  the  least  subject  to  such  attacks  of  all 
the  varieties  of  citrus.  Insect  enemies  of  the  lime,  with  the  exception 
of  the  Mediterranean  fruit  fly,  may  be  kept  under  control  by 
efficient  spraying. 

FLORIDA  RED  SCALE    (Chrysomphalus  aonidum). 

The  Florida  red  scale  is  characterized  by  its  perfectly  circular 
form,  shining  very  dark  brown  or  nearly  black  surface,  and  medial 
lighter  dot.  Its  average  diameter  is  about  one-twelfth  inch  and 
it  appears  in  great  numbers  on  the  underside  of  leaves  and  young 
branches  of  the  lime  tree.  When  infested  with  it  the  foliage  turns 
yellow  and  occasionally  the  tree  dies. 

ORANGE  SCALE   (C.  aurantii). 

The  orange  scale  is  circular  and  flat  in  form.  The  female  varies 
from  one-sixteenth  to  one-eighth  inch  in  diameter,  and  has  a  trans- 
parent scale  through  which  its  red  body  shows.  The  male  is  smaller 
than  the  female  and  of  a  gray  or  dark  brown  color.  The  orange  scale 
is  not  as  serious  a  pest  on  lime  as  it  is  on  other  kinds  of  citrus  trees 
in  Hawaii. 

PURPLE  SCALE   (Lepidosaphes  beckii). 

The  purple  scale  injures  young  branches,  foliage,  and  fruits  of 
the  lime  tree.  The  female  is  oyster-shaped,  often  slightly  curved, 
and  from  one-tenth  to  one-seventh  inch  long  and  about  a  third 
as  wide.  In  color  it  varies  from  light  brown  to  rich  reddish  purple. 
The  male  scale  is  very  narrow  and  smaller  than  the  female. 

MEALYBUGS    (Pseudococcua  filamentosus  and  P.  citri). 

Two  species  of  mealybugs  (P.  filamentosus  and  P.  citri)  have  been 
reported  as  injuring  lime  trees  to  some  extent  in  Hawaii.  These  in- 
sects usually  attack  the  tree  in  time  of  drought,  and  cause  the 
leaves  to  assume  a  malformed  appearance.  These  pests  may  usually 
be  recognized  through  the  distinctive  appearance  and  the  peculiar 
character  of  their  white  waxy  excretion. 

CONTROL. 

Kerosene  emulsion. — This  contact  poison  is  very  effective  in  con- 
trolling scale  insect  pests,  mealybugs,  and  aphids,  provided  it  is 
sprayed  with  some  force  upon  the  trees  infested  with  them.  The 
following  is  the  formula  used  for  making  the  emulsion: 

Laundry  soap   \  pound. 

Water 1  gallon. 

Kerosene 2  gallons. 

The  soap  should  be  thoroughly  dissolved  in  water  while  it  is 
boiling  over  a  fire.  When  the  soap  has  dissolved  the  solution  should 
be  removed  to  a  safe  distance  from  the  fire  and  the  kerosene  slowly 
added  to  it.     The  mixture  should  then  be   agitated  by  charging 


THE   ACID  LIME   FRUIT   IN   HAWAII.  11 

and  discharging  for  about  10  minutes.  When  completed  the  emul- 
sion should  be  creamy  white,  thicken  on  cooling,  and  show  no  trace 
of  free  oil  on  the  surface.  When  used  the  stock  solution  should  be 
diluted  with  8  to  10  parts  of  water. 

Crude  oil  emulsion. — This  emulsion  is  made  in  the  same  way  as  is 
kerosene  emulsion  with  the  exception  that  crude  oil  is  substituted 
for  kerosene.  Crude  oil  does  not  evaporate  as  readily  as  do  the 
refined  and  lighter  oils. 

San-U-Zay  oil. — San-U-Zay  oil  and  water,  in  parts  1  and  35,  re- 
spectively, is  very  effective  in  controlling  aphids  and  mealybugs. 
The  mixture  should  be  thoroughly  agitated  by  means  of  a  wooden 
paddle  before  being  applied  as  a  spray.  The  oil  separates  when 
the  emulsion  is  allowed  to  stand  for  several  days,  but  the  emulsified 
form  is  restored  b}T  stirring  a  little  salsoda  into  it. 

ORANGE  APHIS  (Myzus  citricidus). 

The  orange  aphis  or  black  fly  of  the  orange  is  one  of  the  most 
serious  of  the  pests  attacking  limes.  In  late  winter  or  spring  many 
little  black-winged  flies,  or  green  wingless  insects,  develop  on  the 
young  tender  growth  of  the  tree.  They  are  usually  identified  by 
the  honeydew  which  they  excrete  on  the  leaves  and  stems. 

Control. — Tobacco  water  or  nicotine  sulphate  is  commonly  used 
for  this  sort  of  pest.  A  good  spray  for  black  flies,  mites,  and  thrips 
is  made  as  follows : 

Nicotine  sulphate 1  ounce. 

Laundry  soap 3  or  4  ounces. 

Water 4  gallons. 

To  be  effective  the  spray  must  reach  every  insect. 

The  measures  suggested  for  the  control  of  the  Florida  red  scale 
are  also  efficient  in  controlling  orange  aphids.  The  kerosene  emul- 
sion should,  however,  be  diluted  with  from  10  to  15  parts  of  water 
before  it  is  sprayed  on  the  foliage  infested  with  lice  and  aphids. 

COCKROACHES  (Eleutheroda  dytiscoides) . 

Cockroaches  are  occasionally  reported  as  girdling  and  killing 
young  branches  of  the  lime  tree.  This  species  differs  from  the  com- 
mon cockroach  in  that  the  adults  are  smaller,  of  a  darker  brown 
color,  and  have  smoother  wings.  They  are  most  commonly  found 
among  clusters  of  leaves  or  fruits  growing  in  bunches. 

Poisoned  bait  is  recommended  for  use  as  a  control  measure. 

GREEN  CATERPILLAR    (Plusia  chalcites). 

Green  caterpillars  are  the  larvae  of  small  moths  which  lay  an 
abundance  of  eggs  on  the  foliage  of  lime  trees.  The  larvae  appear  in 
great  numbers  in  spring  and  grow  in  a  few  weeks  to  1J  inches  long. 
They  may  be  identified  by  their  method  of  travel,  looping  along  in 
much  the  same  way  as  do  measuring  worms.  They  are  very  destruc- 
tive to  the  foliage  of  many  kinds  of  plants,  but  especially  to  that  of 
young  seedling  nursery  stock  of  the  lime. 

Control. — As  soon  as  there  is  any  indication  of  injury  from  the 
green  caterpillar,  an  arsenical  poison  should  be  sprayed  on  the  plants 
and  trees.     A  very  efficient  spray  can  be  made  by  mixing  1  ounce 


12        BULLETIN   49;    HAWAII    AGRICULTURAL   EXPERIMENT    STATION. 

arsenate  of  lead  (paste  form)  with  1  gallon  of  water,  or  J  ounce  of 
arsenate  of  lead  (powdered  form)  with  1  gallon  of  water.  Arsenate 
of  lead  is  not  only  much  less  likely  to  injure  the  foliage  than  is  Paris 
green  but  it  is  also  more  effective. 

FULLER'S  ROSE  BEETLE   (Aramigus  fulleri). 

Fuller's  rose  beetle,  commonly  known  in  Hawaii  as  the  Olinda 
beetle,  has  been  found  on  lime  trees  in  some  parts  of  the  Territory. 
The  larvae  live  below  ground  and  feed  upon  plant  roots.  Upon 
reaching  adult  stage  they  eat  the  foliage,  their  method  of  devouring 
the  margins  of  the  leaves  being  a  means  of  their  identification.  The 
beetles  are  incapable  of  flight  and  their  movements  are  slow.  Gener- 
ally they  are  nocturnal  feeders,  but  in  cooler  localities  they  may  be 
found  on  foliage  during  the  day.  The  pest  is  occasionally  kept 
under  control  by  hand  picking  and  by  birds,  especially  by  the  myna 
bird.  Arsenate  of  lead  spraj^  has  been  found  useful  in  their  ex- 
termination. Carbon  bisulphid  may,  under  certain  conditions,  be 
used  to  exterminate  the  larvae  attacking  the  roots. 

MEDITERRANEAN  FRUIT  FLY  (Ceratitis  capitata). 

The  Mediterranean  fruit  fly  was  introduced  into  Hawaii  from 
Australia  about  1907.  The  adult  female  is  a  small  yellow  fly  which 
lays  its  eggs  in  fruit  that  is  nearing  maturity.  Small  white  larva? 
soon  develop  and  after  feeding  on  the  interior  of  the  fruit  enter  the 
soil  to  pupate.  After  it  was  introduced  into  Hawaii  the  pest  spread 
rapidly  and  attacked  many  kinds  of  fruit.  A  careful  study  of  this 
fly  has  been  made  by  Back  and  Pemberton.6 

Control. — Territorial  entomologists  have  done  much  to  control  the 
Mediterranean  fruit  fly  by  introducing  natural  parasitic  enemies 
into  the  island.  About  five  different  species  of  these  natural  enemies 
have,  after  several  years,  succeeded  in  bringing  about  a  great  reduc- 
tion in  the  ravages  of  the  fly.  Lime  and  other  citrus  fruits  which 
were  formerly  severely  ravaged  are  now  comparatively  free  of  attack 
by  the  fly  larvae.  Screens,  nets,  and  paper  bags  are  occasionally  used 
to  protect  the  fruit  from  this  pest. 

FUNGUS  DISEASES. 

BLUE  MOLD    (Penicillium  italicuui). 

Blue  mold  is  sometimes  found  on  fruit  a  few  days  after  it  is  har- 
vested. The  spores  of  this  fungus  lodge  on  the  fruit  in  the  orchard 
and  germinate  when  the  fruit  skin  is  injured  in  any  way. 

BROWN  ROT   (Pythiacystis  citrophthora) . 

Brown  rot  is  a  decaying  of  the  fruit  on  the  tree.  The  fungus  caus- 
ing the  rot  lives  in  the  soil  and  during  wet  weather  develops  spores. 
Affected  fruit  turns  brown  and  the  inner  part  decays. 

ANTHRACNOSE    (Glo?osporium   Hmetticolum). 

Anthracnose,  recently  identified  on  lime  fruits  in  Hawaii  by  the 
Philippine  Bureau  of  Agriculture,  is  a  fungus  disease  which  as  yet 

eU.  S.  Dept.  Agr.  Bui.  536  (1918). 


THE   ACID   LIME   FRUIT   IN    HAWAII.  13 

has  not  proved  serious  in  the  Territory.    It  usually  produces  spot- 
ting of  the  leaves  and  causes  them  to  drop  prematurely. 

CONTROL. 

Fungus  diseases  are  best  controlled  by  Bordeaux  mixture. 
Bordeaux  mixture. — The  general  formula  for  Bordeaux  mixture 
is  as  follows : 

Copper  sulphate    (bluestone) 1  pound. 

Quicklime   (unslaked) 1  pound. 

Water 10  gallons. 

The  copper  sulphate  should  be  suspended  over  night  in  a  sack  in 
a  wooden  receptacle,  such  as  a  sake  barrel  or  a  soja  tub,  containing 
a  gallon  of  water.  Solution  can  be  hastened  by  placing  the  sack 
just  under  the  surface  of  the  water.  If  pulverized  the  copper  sul- 
phate may  be  dissolved  in  half  a  gallon  of  hot  water  to  which  an 
equal  quantity  of  cold  water  is  then  added.  Make  5  gallons  of  the 
copper  solution  by  adding  water.  The  lime  should  be  slaked  sepa- 
rately in  a  small  quantity  of  water.  When  slaking  is  completed, 
add  water  to  make  5  gallons.  Equal  parts  of  the  lime  and  the  copper 
should  be  poured  together  into  a  third  container  and  thoroughly 
stirred  when  the  solution  is  wanted  for  use.  The  solution  should 
then  be  strained  into  the  spray  tank  and  agitated  at  frequent  inter- , 
vals  to  prevent  settling- of  the  precipitate,  formed  by  the  chemical 
union  of  the  lime  and  copper.  Bordeaux  mixture  may  be  kept  with- 
out deterioration  for  some  time  by  the  addition  of  sugar  at  the.  rate 
of  one-tenth  pound  to  10  gallons  of  solution. 

SPRAYING  APPLIANCES. 

A  sprayer  of  any  kind  may  be  used,  but  for  the  sake  of  economy 
and  efficiency  it  should  be  such  as  will  produce  a  fine  misty  spray. 
A  small  pneumatic  hand  pump  having  an  atomizer  type  of  nozzle 
will  distribute  the  liquid  evenly  and  be  perfectly  satisfactory  for 
small  nursery  seedlings,  or  for  use  in  yards  where  there  are  only 
one  or  two  trees.  The  only  drawback  to  such  a  pump  lies  in  the 
difficulty  of  thoroughly  spraying  the  underside  of  the  leaves. 

The  more  complicated  kind  of  pump  having  an  ordinary  type  of 
nozzle  gives  the  best  results  provided  the  application  is  liberal  and 
the  pressure  powerful  enough  to  cause  the  spray  to  settle  in  a  fine 
mist  on  the  trees.  Such  a  pump  is  necessary  where  a  number  of  lime 
trees  are  grown  for  commercial  use. 

A  pump  having  a  5  to  25  gallon  tank  is  useful  for  spraying  small 
orchards,  and  the  knapsack  type  of  sprayer  of  this  size,  when  pro- 
vided with  small  compressed  air  pumps,  gives  considerable  satisfac- 
tion. The  spray  flows  continuously  for  several  minutes  after  the 
air  chamber  is  pumped  up  and  thus  the  operator  is  able  to  give  his 
undivided  attention  to  directing  it. 

A  knapsack  sprayer  which  is  equipped  with  a  3- foot  brass  exten- 
sion rod.  a  stopcock,  and  a  side  disgorger  of  the  cyclone  type,  or  an 
elbow  connection  for  a  nozzle  of  the  Vermorel  type,  has  been  very 
effective  at  the  experiment  station  for  use  in  spraying  both  sides  of 
the  leaves  of  lime  trees. 


14 


BULLETIN  49,  HAWAII   AGRICULTURAL  EXPERIMENT  STATION. 


When  25  or  more  gallons  of  material  are  to  be  applied  at  one  time 
the  spraying  outfit  should  be  mounted  on  a  2-wheeled  cart.  Hand 
pumps  and  barrel  outfits  can  be  drawn  by  mules,  and  similar  outfits 
may  obtain  working  pressure  if  they  are  operated  by  chains  con- 
necting the  pump  with  the  running  gear  of  the  gasoline  engine  or 
wagon.  When  considerable  work  is  to  be  done  several  nozzles  should 
be  attached  and  operated  at  the  same  time. 

COMPOSITION    OF   THE   FRUIT. 

Fruits  of  five  varieties  of  limes  growing  at  the  Hawaii  Experi- 
ment Station  were  analyzed  in  February,  1922.  Tables  3  and  4  give 
the  results  of  the  analyses. 

Tahle  3. — Composition  of  five  varieties  of  limes  growing  at  the  Hawaii  Station. 


Variety. 


Kusaie 

West  Indian  or  Mexican 

Tahiti  i 

Rangpur 


Aver- 
age 
weight 
per 

fruit. 


Grams. 
61.5 
26.9 

155.0 
84.0 

124.2 


Propor- 
tion of  ;  Propor- 


rind 

and    {  seeds 
pulp. 


Propor 


tion  of    tion  of 
juice. 


P.ct. 

39.36 
44.  55 
41.42 
49.2 
41.22 


P.ct. 

2.29 

.86 

.11 

1.37 

(2) 


P.ct. 
58.35 

54.  59 
58.47 
49.43 
58.78 


Composition  of  juice. 


Total 
solids. 


P.ct. 
9.0 
8.7 
9.5 
8.4 
11.6 


P  educ- 

Citric 

ing 

acid. 

sugar. 

P.ct. 

P.ct. 

0.81 

6.75 

.22 

7.45 

.77 

7.43 

1.17 

6.10 

1.69 

8.32 

Pro- 
tein. 


P.ct. 
0.381 
.281 
.388 
.375 
.338 


i  The  Tahiti  "seedless"  lime  occasionally  possesses  some  seeds,  possibly  due  to  pollination  vrith  near 
varieties  blooming  at  the  same  time. 
2  None. 

Table  4  compares  the  composition  of  several  kinds  of  citrus  fruits. 
Table  4. — Composition  of  Hawaiian  citrus  fruits.1 


Kind  of  citrus. 

Edible 
por- 
tion. 

Waste. 

Total 
solids. 

Insolu- 
ble 
solids. 

Acid.* 

Ash. 

Pro- 
tein. 

Fat. 

Fiber. 

Lxmes 

P.  ct. 
49.17 
33.14 
72.13 
42.39 

P.ct. 
50.83 
66.86 
27.87 
57.61 

P.ct. 
11.75 
6.  44 
12.15 
11.53 

P.  ct. 

0.11 

.30 

2.57 

6.14 

P.  ct. 
9.630 
4.753 
1.243 

.276 

P.ct. 

0.352 

.232 

.453 

.486 

P.ct. 

0.675 
.356 
.681 

1.175 

P.ct. 

3.561 

1.490 

.387 

.140 

P.ct. 
0.065 

Lemons  trough) 

.084 

Oranges  (Kona) 

.575 

Shaddocks 

1.977 

Sugars.                                    Polarization. 

Kind  of  citrus. 

Reduc- 
ing. 

Sucrose.  '    Total.       Direct. 

Invert. 

Tempera- 
ture. 

Limes 

Per  cent. 

1.50 

1.53 

2.09 

.86 

Per  cent.  !  Per  cent.  '      °  V. 

(3)                 1.50           -0.4 

0.47  i          2.00           +2.2 

3.81  j          5.90           +3.5 

7.26            8.12  i        +7.6 

°  V. 
-0.2 
+  1.6 
-1.4 
-1.6 

0  C. 
31.5 

Lemons  ( rough) 

32.3 

Oranges  (Kona) 

28.3 

Shaddocks 

31.8 

*- 1 

i  From  Hawaii  Sta.  Rpt.  1914,  p.  67. 

1  As  citric  acid  instead  of  as  sulphuric  acid,  as  given  in  the  original  analysis. 

5  None. 


In  preparing  the  samples  for  analyses  the  lemons  and  limes  were 
squeezed  to  obtain  the  juice.     The  oranges  and  shaddocks  were  peeled 


THE   ACID  LIME   FRUIT  IN   HAWAII.  15 

and  the  whole  pulp  was  ground.  The  acid  content  of  the  lime  is 
naturally  high.  The  rather  high  fat  content  in  the  limes  and  lemons 
was  doubtless  due  to  oil  from  the  peel. 

COMMERCIAL  PRODUCTS. 

The  growing  demand  for  the  various  commercial  products  of  the 
lime  has  created,  considerable  interest  in  lime  culture,  particularly 
in  the  West  Indies  and  Ceylon.7 

Green  limes. — The  remoteness  of  the  place  of  production  from  the 
general  market  makes  it  profitable  to  ship  only  especially  selected 
fresh  green  limes.  They  are  usually  packed  in  barrels  holding  some 
1,500  fruits  each.  At  present  the  island  of  Dominica,  W.  L,  which 
exports  about  42,000  barrels  annually,  supplies  most  of  the  world 
markets  with  fresh  limes. 

Pickled  limes. — Salt-pickled  limes  are  made  from  selected  yellow 
fruit,  which  is  steeped  in  several  changes  of  sea  water  and  then 
packed  in  stronger  brine  at  the  rate  of  2,000  fruits  per  cask.  The 
demand  for  pickled  limes  has  been  on  the  decline  within  recent 
years. 

Raw  lime  juice. — This  product  is  expressed  by  passing  sound, 
clean  limes  between  heavy  granite  rollers.  The  juice  is  clarified  by 
being  allowed  to  stand  until  the  albuminous  matter  forms  a  precip- 
itate, after  which  it  is  filtered  and  sealed  air-tight.  It  can  be  kept 
for  several  months  in  this  condition  without  serious  loss  of  citric 
acid  by  fermentation.  The  presence  of  essential  oil  from  the  rind 
is  thought  to  prevent  the  possibility  of  loss  of  acid,  and  for  this 
reason,  as  well  as  from  considerations  of  color  and  cost,  raw  lime 
juice  is  not  distilled.  It  is  used  principally  in  the  preparation  of 
beverages. 

Concentrated  lime  juice* — This  product  is  prepared  mainly  for 
the  purpose  of  reducing  bulk  and  consequently  freight  charges  en- 
tailed in  the  shipment  of  the  raw  juice.  The  latter  is  concentrated 
to  a  sirup  by  the  simple  process  of  boiling  in  a  steam-heated  or  other 
efficient  evaporator,  a  process  which  reduces  the  bulk  from  one- 
seventh  to  one-twelfth  of  its  original  volume,  the  degrees  of  concen- 
t  ration  varying  with  the  strength  of  the  milled  juice.  Concentrated 
lime  juice  is  exported  chiefly  for  use  in  dye  works  and  pure  chemical 
preparations. 

Citrate  -of  lime  or  calcium  citrate. — For  various  reasons  citrate  of 
lime  or  calcium  citrate  is  replacing  concentrated  lime  juice  as  a  com- 
mercial product.  Great  care  must  be  exercised  in  the  preparation 
of  the  concentrated  lime  juice;  otherwise  a  very  dark  product  will 
result  and  the  crystals  of  citric  acid  will  be  discolored  and  require 
expensive  purification.  Again,  leakage  from  casks  and  the  difficulty 
of  obtaining  suitable  casks  in  the  Tropics  are  important  commercial 
considerations. 

Citrate  of  lime,  when  properly  prepared,  is  a  white  powder  that 
can  be  shipped  anywhere  in  paper-lined  barrels  and  it  wilr  keep  in- 

7  AucMnleck,  G.  G.  The  cultivation  of  limes.  In  Trop.  Agr.  [Ceylon],  57  (1921), 
No.  5,  pp.  284-20S. 

8  Information  relative  to  the  concentrated  lime  juice  and  citrate  of  lime  industry  of 
the  West  Indies  is  given  in  West  Indian  Buls.  2  (1901).  No.  4,  p.  308;  7  (1906),  No.  4. 
p.  331;  8  (1907).  No.  2,  p.  107;  9  (1908),  No.  2,  p.  193;  12  (1912),  No.  4,  p.  405;  and 
Agr.  News,  1   (1902),  No.  7,  p.  99. 


16       BULLETIN  49,   HAWAII   AGRICULTURAL  EXPERIMENT   STATION. 

definitely  in  storage.  At  present  the  preparation  of  citrate  of  lime 
in  the  country  where  the  fruit  is  grown  is  a  step  in  the  manufacture 
of  citric  acid.  The  citrate  is  prepared  from  clear  filtered  lime 
juice  neutralized  by  the  addition  of  chalk  or  lime.  The  juice  must 
be  hot  and  the  chalk  or  lime  very  fine  and  free  from  magnesium 
and  other  impurities.  The  chalk  or  lime  is  stirred  in  water  to  the 
consistency  of  cream,  after  which  it  is  poured  into  the  hot  juice, 
the  whole  being  constantly  stirred.  When  the  chalk  or  lime  is  added 
an  active  foaming  or  effervescence  takes  place,  which  diminishes 
as  the  neutralization  point  is  reached.  The  amount  of  chalk  or  lime 
to  be  added  may  be  determined  by  removing  a  small  sample  from 
time  to  time  and  testing  it  by  adding  more  chalk.  This  is  repeated 
until  no  active  effervescence  takes  place.  Finally,  a  few  drops  of 
lime  juice  should  be  added  to  a  sample  of  the  mixture.  "  If  only 
slight  effervescence  occurs  the  proper  amount  of  chalk  has  been 
added,  but  if  strong  foaming  takes  place  more  juice  should  be  added 
to  the  mixture.  The  mixture  should  be  heated  to  nearly  the  boiling 
point  for  a  few  minutes,  when  the  citrate  of  lime  will  begin  to  fall- 
as  a  precipitate.  The  clear  yellow  liquid  is  then  poured  off  and  the 
precipitate  washed  with  hot  water,  after  which  it  is  dried  and  packed 
for  storage  and  shipment.  Commercial  citrate  of  lime  contains 
about  65  per  cent  of  citric  acid. 

Citric  acid  is  obtained  from  the  citrate  of  lime  by  adding  dilute 
sulphuric  acid,  which  produces  sulphate  of  lime,  leaving  citric  acid 
in  solution.  The  solution  is  evaporated  in  leaden  boilers  until  the 
pure  citric  acid  crystallizes  out.    Citric  acid  has  many  uses. 

Essential  oils. — A  very  volatile  essential  oil  of  high  flavor  is  ob- 
tained from  the  rind  of  the  lime.  The  market  recognizes  two  classes 
of  oil,  depending  upon  the  method  of  extraction.  The  higher  grade 
of  oil,  or  "otto,"  is  extracted  from  the  rind  by  hand  pressure,  the 
fruits  being  rolled  individually  on  a  spiked  funnel  known  as  an 
"  ecuelle."  The  method  is  slow  and  requires  a  long  time  to  collect 
oil  in  any  quantity.  After  the  fruits  have  been  so  treated  they 
are  milled  and  the  juice  and  a  further  yield  of  oil  are  extracted  by 
pressure.  The  oil  is  then  separated  from  the  juice  by  distillation 
and  is  considered  as  second-grade  oil. 

Lime  oil  is  in  demand  for  flavoring  extracts  and  perfumery. 

RECIPES  FOR  USING  LIMES.* 

Lime  juice  makes  an  excellent  flavoring  for  various  kinds  of  food. 
In  addition  to  being  substituted  for  vinegar  in  many  recipes,  it  is 
used  as  a  seasoning  for  mayonnaise  and  the  French  dressing  which 
is  served  with  many  kinds  of  tropical  fruits  and  in  certain  kinds 
of  fresh  salads.  It  is  also  used  to  improve  the  flavor  of  jams,  jellies, 
and  fruit  butters. 

FRESH  LIMES. 

Sound  limes. 

Mason  fruit  jars  having  air-tight  caps. 

Select  clean,  sound  fruit  which  has  been  cut  from  the  tree  in  such  a  way  as 
to  leave  the  little  stem-end  disks  or  "buttons"  adhering  to  the  fruit.  These 
prevent  the  entrance  of  fungus  spores  which  cause  decay.  To  keep  limes  for 
several  weeks,  place  them  in  a  fruit  jar  fitted  with  air-tight  cap. 

8  The  writer  is  indebted  to  Mrs.  N.  A.  Russell,  collaborator  in  home  economics,  this  i 
station,  for  recipes  5,  11,  12,  13,  14,  and  15,  and  to  H.  L.  Chung,,  specialist  m  tropical 
agronomy  of  the  station,  for  recipe  10. 


THE   ACID  LIME   FRUIT  IN   HAWAII. 


17 


LIMEADE. 

2  teaspoonfuls  of  sugar.  I  1  lime. 

£  glassful  of  ice  water. 

Put  sugar  in  glass,  add  ice  water,  and  stir  until  the  sugar  has  dissolved; 
then  add  the  juice  of  one  lime.  Serve  immediately.  Soda  water  or  boiled 
water  with  cracked  ice  may  be  substituted  for  ice  water. 

GRAPE  JUICE  LIMEADE. 


1^  pints  of  water. 
1  pint  of  grape  juice. 


1  small  piece  of  ice. 

Juice  of  5  limes. 

1  cupful  of  granulated  sugar. 

Sufficient  for  six  people. 

Place  ice  in  pitcher,  add  lime  juice,  sugar,  water,   and  grape  juice, 
thoroughly.     Let  stand  for  several  minutes,  then  serve. 


Stir 


LIMES    WITH   ICED    TEA. 


Hot  tea  of  the  strength  desired. 


Sliced  limes. 


Serve  tea  hot  with   sliced  limes  and  sugar  separately  to  be   combined   as 
desired. 

LIMES  WITH  ICED  TEA. 


2  teaspoonfuls  of  tea.  |  2  limes. 

2  cupfuls  of  boiling  water.  |  Crushed  ice. 

Pour  boiling  water  over  tea ;  let  stand  for  5  minutes ;  then  strain  into  glasses 
half  filled  with  crushed  ice.     Serve  half  a  lime  to  the  glass  and  sugar  to  taste. 


AFTERNOON   TEA. 


3  teaspoonfuls  of  tea. 

2  cupfuls  of  boiling  water 

1  lime. 


Cloves. 

Candied  cherries. 

Loaf  sugar. 


Make  the  tea  in  teapot  or  with  tea  ball ;  let  stand  for  several  minutes ;  then 
serve,  placing  in  each  cup  a  slice  of  lime  pierced  with  a  clove.  Add  a  cherry 
and  serve  sugar  separately  in  such  quantities  as  may  be  desired. 

LIME-JUICE  COCKTAIL. 


4  tablespoonfuls  of  lime  juice. 
2  tablespoonfuls  of  orange  juice. 
2  tablespoonfuls  of  sugar  sirup. 

Place  ingredients  in  cocktail  shaker 
four  cocktail  glasses.     Serve. 


§  cupful  of  ginger  ale. 
Crushed  ice. 


shake,  and  pour  over  crushed  ice  in 


OYSTERS  WITH   LIME   COCKTAIL  SAUCE. 


12  drops  of  Tobasco  sauce. 

\  teaspoonful  of  grated  horseradish. 

24  oysters  on  the  half  shell.  . 

Salt. 


4  ripe  limes. 

3  tablespoonfuls  of  lime  juice. 
2  tablespoonfuls  of  tomato  catsup. 
1  tablespoonful     of     finely     chopped 
onions. 

Cut  off  one-third  of  each  lime,  remove  pulp  and  juice,  leaving  a  basketlike 
container.  Mix  lime  juice  with  the  other  seasonings,  adding  salt  to  taste. 
Put  the  mixture  in  the  baskets  and  place  in  the  center  of  deep  plates  of 
crushed  ice.     Surround  each  basket  with  six  oysters  and  serve  for  first  course. 


LIME   WITH   FISH. 

Squeeze  juice  of  two  limes  over  fish  when  ready  to  bake.  Add  more  lime 
juice  while  fish  are  baking,  if  desired.  Garnish  with  parsley  and  slices  of  lime. 
Serve  fish  with  sauce. 


18       BULLETIN  49,   HAWAII   AGRICULTURAL  EXPERIMENT  STATION 


PICKLED   LIMES    (CHINESE  METHOD). 


Limes.  ]    Large  glass  jars  fitted  with  airtight 

Coarse  salt.  caps. 

Granulated  sugar. 

Wash  limes  thoroughly ;  expose  them  to  sun  for  two  or  three  hours  to  dry  out 
surplus  water;  rub  salt  into  limes  while  they  are  warm  from  the  sunning,  and 
again  once  or  twice  each  day"  for  the  next  four  or  five  days,  after  they  have 
been  exposed  to  the  sun.  At  the  end  of  that  time  place  salted  lines  in  large 
glass  jars  having  air-tight  caps.  Sprinkle  surface  with  coarse  salt  before 
placing  the  cap.  Expose  the  jars  of  pickling  limes  to  the  sunlight  for  two  or 
more  months  to  cure  limes  thoroughly  before  opening  jars.  When  properly 
cured,  pickled  limes  vary  in  color  from  light  brown  to  dark  mahogany.  When 
serving,  remove  the  number  of  limes  desired,  sprinkle  with  granulated  sugar 
(one-half  teaspoonful  of  sugar  to  each  pickled  lime),  and  then  partly  mash. 
They  may  be  served  with  meat,  rice,  and  the  like. 

LIME  SIRUP. 


(For  cold  drinks,  ice  cream,  sauce,  etc.) 

2  dozen  ripe  limes.  I    \  cupful  of  water. 

1  pound  of  cube  sugar. 

Wash  the  limes  thoroughly  in  cold  water  and  dry.  Rub  the  sugar  vigorously 
all  over  the  lime  until  it  loses  its  color.  Squeeze  the  juice  on  the  sugar,  add 
water;  then  boil  and  strain.  For  cold  drinks,  place  2  tablespoonfuls  of  the 
sirup  in  a  tumbler  with  crushed  ice  and  fill  with  plain  water. 

LIMES   IN   PAPAYA  BUTTER. 

To  every  4  cupful s  of  ripe  mashed  papaya  add  one-half  cupful  of  lime  juice 
and  2  cupfuls  of  sugar.  Stir  constantly  over  a  brisk  fire,  cooking  for  20 
minutes. 

LIME  CAKE  FILLER. 


1  cupful  of  water. 

2  tablespoonfuls  of  butter. 

2  eggs. 


4  tablespoonfuls  of  flour.  ■ 

4  tablespoonfuls  of  white  sugar. 

1  pinch  of  salt. 

4  small  limes. 

Sift  together  the  flour,  sugar,  and  salt.  Squeeze  the  juice  from  the  limes,  add 
water,  and  heat.  When  boiling,  add  butter  and  pour  into  the  mixture  of  flour, 
sugar,  and  salt,  stirring  well.  Add  the  well-beaten  eggs  and  return  to  the  fire 
until  the  mixture  is  smooth.     Place  between  layers  of  cake  and  frost  all  over. 

LIME   CREAM-PUFF   FILLER. 

Make  the  same  as  for  cake  filler  (preceding  recipe),  adding,  when  cold, 
one-half  cupful  of  whipped  and  sweetened  cream.  Fill  the  puff  just  before 
serving. 

LIME   PIE   FILLING. 


fi  limes. 

1  cupful  of  water. 

4  tablespoonfuls  of  sugar. 


2>  tablespoonfuls  of  butter, 
4  tablespoonfuls  of  flour. 
2  eggs. 


Wash  the  limes  well,  remove  a  few  thin  slices  of  the  skin,  and  chop  fine. 
(There  should  be  a  level  half  teaspoonful  of  chopped  skin.)  Squeeze  and 
strain  the  juice.  Boil  the  water  and  add  sugar,  juice,  and  chopped  skin.  Melt 
the  butter  in  a  pan,  stir  in  the  flour,  and  add  the  liquid,  stirring  until  boiling. 
Place  the  whites  of  eggs  on  ice,  beat  the  yolks,  and  pour  the  hot  mixture  onto 
them,  stirring  briskly.  Pour  into  a  pie  plate  lined  with  pastry  and  bake  until 
set  and  the  pastry  is  cooked.  Whip  the  whites  to  a  stiff  froth  and  add  a  little 
sugar.  Pipe  on  to  the  lime  mixture  and  set  again  in  the  oven  until  the  filling 
becomes  a  delicate  brown.    Serve  either  hot  or  very  cold. 


THE  ACID  LIME   FRUIT  IN   HAWAII.  19 

LIME   CANDY. 

4  cupfuls  of  granulated  sugar.  I   |  cupful  of  water. 

2  tablespoonfuls  of  lime  juice.  |  2  tablespoonfuls  of  butter. 

Mix  ingredients  together  and  cook  until  a  soft  ball  is  formed  when  tested  in 
cold  water.  Remove  from  the  fire  and  beat.  Turn  into  buttered  dishes  and 
mark  into  squares  while  warm,  or  knead  until  creamy  and  shape  as  desired. 

BOTTLED   LIME   JUICE. 

Limes.  |  Bottles,  1  or  2  pint  capacity. 

Extract  the  juice  from  the  limes,  clarify  by  settling  and  straining;  then  fill 
into  bottles  and  keep  tightly  corked.  The  juice  can  be  kept  in  this  way  for 
several  months  without  serious  deterioration. 

SUMMARY. 

The  acid  lime  fruit,  which  is  closely  related  to  the  lemon,  orange, 
mandarin,  pomelo,  and  shaddock,  was  introduced  into  Hawaii  early 
in  the  nineteenth  century  and  seems  to  be  the  best  adapted  of  any  of 
the  citrus  fruits  to  island  conditions. 

The  tree  can  be  propagated  in  several  ways,  produces  a  large  crop 
of  fruit  during  the  greater  part  of  the  year,  withstands  drought  re- 
markably well,  and  is  not  as  susceptible  to  insect  attack  as  are  most 
of  the  other  citrus  fruits. 

It  thrives  best  in  a  warm,  moist  climate  where  the  rainfall  is  evenly 
distributed  in  frequent  showers,  and  is  not  particular  as  to  soil  type, 
although  it  needs  rich,  well-drained,  and  thoroughly  tilled  sandy  or 
gravelly  soil  for  best  development. 

The  lime  tree  should  be  furnished  with  an  abundance  of  plant  food 
in  the  form  of  fertilizing  material,  either  as  barnyard  manure  or 
commercial  fertilizers,  singly  or  in  combination,  to  maintain  heavy 
bearing.  Vigorous  tree  growth,  dark  green  foliage,  and  a  small 
amount  of  fruit  having  thick  rind  and  very  fibrous  pulp  indicate  the 
presence  in  the  soil  of  excessive  nitrogen.  Liberal  applications  of 
potash  with  the  nitrogen  tend  to  produce  greater  fruit  fulness,  thin- 
ness of  rind,  and  less  fiber.  In  general  fruit  culture  it  is  thought  that 
young  trees  require  phosphoric  acid,  potash,  and  nitrogen  in  the  pro- 
portions of  6,  8,  and  4  per  cent,  respectively,  and  that  fruiting  trees 
require  them  in  the  proportions  of  8,  12,  and  3^  per  cent,  respectfully. 

Both  seedlings  and  grafted  stock  should  be  at  least  a  year  old  be- 
fore they  are  transplanted  to  their  permanent  location.  Young  trees 
may  be  set  in  hedge  formation  and  developed  into  a  wide  fence  for 
the  production  of  a  large  quantity  of  fruit  from  a  small  area. 

Four  varieties  of  limes,  with  possibly  their  closely  related  species, 
were  experimented  upon  by  the  station.  Of  these,  Kusaie  is  consid- 
ered the  finest,  having  abundant  colorless  or  transparent  juice  and 
few  seeds.  Each  tree  of  this  variety  produced  in  its  fourth  year 
at  this  station  about  400  fruits  averaging  40  pounds  per  tree. 

The  growing  demand  for  the  various  commercial  products  of  the 
lime  has  created  considerable  interest  in  lime  culture.  Salt-pickled 
limes  are  made  from  the  selected  yellow  fruit,  and  raw  lime  juice  is 
expressed  from  clean,  sound  limes  and  after  being  clarified  is  used 
principally  in  the  preparation  of  beverages.  Green  limes  are  shipped 
to   market,   usually   packed   in   barrels   holding   about   1,500    fruits 


20       BULLETIN  49,   HAWAII   AGRICULTURAL  EXPERIMENT  STATION. 

each.  Concentrated  lime  juice,  which  is  prepared  mainly  for  the  pur- 
pose of  reducing  bulk  and  consequently  the  freight  charges  entailed 
in  the  shipment  of  the  raw  juice,  is  exported  for  use  in  dye  works 
and  pure  chemical  preparations.  Citrate  of  lime  or  calcium  citrate 
is  replacing  concentrated  lime  juice  as  a  commercial  product.  When 
properly  prepared  it  can  be  shipped  anywhere  in  paper-lined  barrels 
and  will  keep  indefinitely  in  storage.  Citric  acid  is  obtained  from 
the  citrate  of  lime  by  adding  dilute  sulphuric  acid,  which  removes 
the  lime  and  leaves  the  citric  acid  in  solution.  Citric  acid  has 
many  uses.  A  very  volatile  essential  oil  of  high  flavor  is  obtained 
from  the  rind  of  the  lime.  Lime  oil  is  in  demand  for  flavoring  ex- 
tracts and  for  perfumery. 

The  rapidly  increasing  population  and  widespread  demand  for  the 
lime  fruit  seem  to  assure  local  development  of  the  lime-fruit  industry. 


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COPY   FOR   PROFIT.— PUB.   RES.  57,  APPROVED   MAY   11,   1922 

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